This application and its disclosure generally relate to the field of determining orientation of a human head in three-dimensional geometric modeling and then using this orientation in stereotactic brain surgery.
Head orientation measurements in 3D geometric modeling are currently based on a combination of measurements determined by different gyroscopes, accelerometers and electronic compasses. For example, one such system is based on measurements provided by a three-axis accelerometer and a resonator gyroscope mounted on a headgear.
Other methods and measuring systems, currently in use, utilize dual inclinometers, bubble goniometers, radiographs, compass technology, visual estimation, ultrasound, geometric methods, digital optoelectronic instruments, computerized kinematic analysis using passive markers and infrared TV cameras, MRI or sensors attached to the subject's head for head orientation determination. However, none of the existing methods yield a sufficient accuracy in defining the neutral position of a human head in three-dimensions.
This lack of a precise definition of the neutral position of the 3D orientation of the human head is a serious disadvantage in current 3D geometric modeling, especially when one needs to determine some specific measurements and orientation of the human head during motion. In certain applications, for example in dental arts and in stereotactic brain surgery, the existing methods result in significant errors and distortions in the subject's measurements and, consequently, in the resulting 3D model.
A stereotactic brain surgery is a surgical procedure where lesion, frequently, a brain tumor, is removed with the assistance of image guidance. Images used in this process are typically obtained prior to the surgery to allow the surgeon to study the exact location of the lesion and to develop a surgical plan, i.e., to create a pathway through the brain for safe removal of as much abnormal tissue as possible while leaving normal, healthy brain relatively intact. Stereotactic brain surgery is typically performed with a computer system which integrates an image obtained through a special MRI or CT performed one or two days before the surgery. This image is then imported into the computer system which provides doctors with a 3-dimensional image of the subject's brain and of the intended target. Surgeons later use this image to guide their removal of the target lesion. In order to obtain the image and to subsequently to perform the surgery, a neurosurgical head holder (skull clamp) system is used to secure the patient's head position during surgical procedures. The system may include a head holder frame that attaches to the operating table, skull clamp, neurosurgical head hold stabilization components, skull pins and other accessories. Because, positioning of the neurosurgical head holder during image taking does not exactly correspond to its positioning during the surgery, and, generally, is not 100% precise every time, the image on the computer system often does not precisely coincide with the actual brain topography at the surgeon's table. Because the surgeon relies on this image during the surgery, this imprecision sometimes results in severe damage to the patient's brain.